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1.
Cobalt oxide (Co3O4) nanoparticles were successfully synthesized by the cetyltrimethylammonium bromide (CTAB)-assisted method at normal pressure for the first time. The structure and morphology of the as-prepared Co3O4 nanoparticles were characterized by powder X-ray diffracton (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2-sorption analysis. XRD studies indicated that the as-prepared product was well-crystallized cubic phase of Co3O4 with a cell constant of α = 8.0722 Å. The EM images showed that the obtained Co3O4 sample consisted of dispersive quasi-spherical particles with the size ranged from 15 to 25 nm. 相似文献
2.
Co3O4 hollow spheres were hydrothermally prepared at 130 °C for 16 h in the presence of Poly-vinylpyrrolidone (PVP). The as-prepared products were characterized by powder X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), infrared spectrum (IR), X-ray photoelectron spectrum (XPS), and optical absorption spectrum. PVP surfactant plays important roles in the formation of Co3O4 hollow spheres. These Co3O4 hollow spheres have average diameters of ca. 350 nm, and the wall thickness around the shell is about 42 nm. The possible formation mechanism of hollow Co3O4 spherical structures has simply been proposed. 相似文献
3.
PbBi2Nb2O9 nanocrystals with a perovskite-type structure were successfully synthesized at a relative low temperature via a citrate complex method. Metal ions were dispersed by citric acid in ethanol and ethylene glycol solvent, and then reacted with NH4H2[NbO(C2O4)3·3H2O] to form the gel. XRD results showed that pure PbBi2Nb2O9 nanocrystals could be obtained after calcined treatment of xerogel at 800 °C. The average particles size was 57 nm. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that the sintering process led to the agglomeration of the nanoparticles. The photocatalytic test showed that the sample prepared by the citrate complex method exhibited a higher photocatalytic activity than that of the sample prepared by the solid-state reaction. 相似文献
4.
Yanhuai Ding Ping Zhang Zhilin Long Yong Jiang Jiangnan Huang Gui Liu 《Materials Letters》2008,62(19):3410-3412
Co3O4 nanofibers as anode materials for lithium-ion batteries were prepared from sol precursors by using electrospinning. The morphology, structure and electrochemical properties of Co3O4 nanofibers were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and charge-discharge experiments. The results show that Co3O4 nanofibers possessed typical spinel structure with average diameter of 200 nm. The initial capacity of Co3O4 nanofibers was 1336 mAhg− 1 and the capacity reached 604 mAhg− 1 up to 40 cycles. It was suggested that the high reversible capacity could be ascribed to the high surface area offered by the nanofibers' structure. 相似文献
5.
Spinel CoCo2O4 nanotubes and porous nanostructures have been synthesized by a novel hydrothermal method from Co(NO3)2·6H2O in mixtures of ammonia and cyclohexane at 220 °C. The morphology and phase of CoCo2O4 can be controlled by adjusting the experimental parameters that include the Co2+ concentration and the volume ratio of ammonia to cyclohexane. X-ray diffraction and transmission electron microscopy analyses were used to characterize the products. The formation mechanisms of CoCo2O4 nanostructures is proposed in detail. The electrochemical properties of the as-prepared samples have been investigated. 相似文献
6.
Co3O4-RuO2 composite nanofibers (NFs) were synthesized by an electrospinning method and were calcinated at 400°C for 1 hr in air. Scanning electron microscopy and high-resolution transmission electron microscopy (HRTEM) examinations show that all the synthesized NFs have uniform surface morphology and their diameters are in the range of ~ 30-~70 nm. X-ray diffraction (XRD) results show that crystalline Co3O4 phase and RuO2 phase coexist in the composite NF matrix which is confirmed by X-ray photoemission spectroscopy. In addition, the HRTEM energy-dispersive X-ray spectroscopy mapping results show that the Co3O4 and RuO2 phases are uniformly distributed across the NF matrix. 相似文献
7.
The novel Co3O4 cubic nanoframes, sized in ca. 30 nm, were firstly fabricated via a facile solvothermal route. Based on the transmission electron microscopy and the powder X-ray diffraction analyses of the time-dependent products, a mechanism of facet-preferential chemical etching of Fe3+ ions to the pre-synthesized Co3O4 nanocubes is proposed for the formation of Co3O4 cubic nanoframes. This synthetic strategy can probably be extended to fabricate nanoframes of some other binary metal oxides, by designing similar chemical etching process. 相似文献
8.
Xingfei Ke Mingbo Zheng Yongping Chen Jinsong Liu Guangbin Ji 《Materials Letters》2007,61(18):3901-3903
The synthesis of the single-crystal Co3O4 nanorods by molten salt approach was reported for the first time. The products were characterized by Transmission electron microscopy (TEM), X-ray diffraction (XRD), High-resolution transmission electron microscopy (HRTEM) and Selected-area electron diffraction (SAED). TEM results indicate that these nanorods have diameters of about 150 nm and lengths of about 2 μm. According to the analysis of the SAED and HRTEM results, we drew the conclusion that these nanorods grew along an unusual [− 1,− 1,15] direction by Ostwald ripening mechanism. 相似文献
9.
In2O3 octahedrons were synthesized by carbothermal reduction method. The products were characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDX), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction analysis (SAED) and room-temperature photoluminescence (PL) spectra. The results show that the products are single-crystalline In2O3 octahedrons with the arrises length in the range of 400-3000 nm. The PL spectra displays blue and green emission peaks which can be indexed to default and oxygen vacancies; blue-shift and intensity decrease was observed when excitation wavelength decreases from 380 nm to 325 nm. The growth mechanism of the In2O3 octahedrons is discussed. 相似文献
10.
Changyong LanJiangfeng Gong Zhiqiang WangShaoguang Yang 《Materials Science and Engineering: B》2011,176(8):679-683
The synthesis of single crystalline K6Ta10.8O30 nanowires by molten salt method was reported for the first time. X-ray diffraction results indicated that the as-prepared products were pure phase K6Ta10.8O30. Scanning electron microscopy and transmission electron microscopy results showed that the products consisted of wire-like nanostructures with 100-300 nm in diameter and several micrometers in length. High resolution electron microscopy and selected area electron diffraction results indicated that the K6Ta10.8O30 nanowires were single crystalline with a growth direction of [0 0 1]. The ultraviolet-visible diffuse reflectance measurement showed that the band gap of the nanowires was about 4.1 eV. The effects of reaction temperature, time, and weight ratio of the precursor (mixture of K2CO3 and Ta2O5) to KCl salt on the morphology of the products were investigated. 相似文献
11.
Lithium niobate crystal was successfully synthesized via hydrothermal synthesis method using LiOH·H2O or LiNO3 and Nb2O5 as starting materials in water or ammonia solution. X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectra and Scanning electron microscopy (SEM) were used to characterize the as-prepared samples. The synthesis conditions such as crystallization temperature and time as well as ammonia concentration (when using LiNO3 as Li source) were investigated. The results demonstrate that the crystallization and purity of the as-prepared samples were increased with the increase of time when temperature was at 260 °C. When using LiNO3 as Li source a basic solution was necessary to synthesize LiNbO3. In the present work ammonia solution was used instead of water to obtain alkalescence solvent. XRD results revealed that the as-prepared samples had a hexagonal structure. FT-IR results displayed that the LiNbO3 phase could be completely formed and no secondary phase was found under proper conditions. SEM picture showed that the morphology of the sample was more perfect and bigger with increasing reaction time. 相似文献
12.
Shibing Ni Xinghui Wang Guo Zhou Feng Yang Junming Wang Qi Wang Deyan He 《Materials Letters》2009,63(30):2701-2703
Well dispersed Fe3O4 nanoparticles with a mean diameter of about 160 nm were synthesized by a simple hydrothermal method in the presence of sodium sulfate. The products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Raman spectrum, and Fourier transform infrared spectra (FTIR). Electrochemical properties of the nanostructured Fe3O4 as cathode electrodes of lithium ion battery were studied by conventional charge/discharge tests, showing a high initial discharge capacity of 1267 mA h g− 1 at a current density of 0.1 mA cm− 2. 相似文献
13.
Co2P nanocrystals were successfully synthesized by a polymer-assisted hydrothermal method. The reaction was carried out at 190 °C-220 °C using cobalt chloride hexahydrate (CoCl2·6H2O) as Co-source and yellow phosphorous as P-source. Polyacrylamide (PAM) was used as surfactant. By controlling the experiment parameters such as the reaction temperature and the amount of polyacrylamide (PAM), Co2P nanocrystals with the rod-like or flower-like morphology could be prepared successfully. The phase and the morphology of the samples were characterized by X-ray diffraction (XRD), transmission electron microscopes (TEM), electron diffraction pattern (ED) and high resolution transmission electron microscope (HRTEM). Furthermore, based on the results of the TEM observation, the possible formation processes of the Co2P nanorods or nanoflowers were also discussed. 相似文献
14.
One-step reaction was designed to synthesize mono-dispersed Ag/Fe3O4 micro-sphere with different Ag content via a facile and easily controlled hydrothermal method without use of any surfactant. The phases and composition analysis of the as-prepared samples were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The morphology of the samples was observed by transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FE-SEM). The results revealed that the Ag/Fe3O4 composite samples with different Ag content were micro-spheres with almost the identical size of 175 nm or so in diameter. The electrocatalytic activity of the resultant samples modified on a glassy carbon electrode (GCE) for p-nitrophenol reduction in a basic solution was investigated. The results indicated that all the samples exhibited enhanced electrocatalytic activity for p-nitrophenol reduction, and the sample with 3% Ag exhibited the highest electrocatalytic one. 相似文献
15.
Monodisperse α-Fe2O3 nanoparticles have been successfully prepared by hydrothermal synthetic route using FeCl3, CH3COONa as reagents and reacted at 200 °C for 12 h. The morphology and structure of products were characterized by powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results showed that the α-Fe2O3 nanoparticles were single-crystalline hexagonal structure and average diameters were about 80 nm. Magnetic properties have been detected by a vibrating sample magnetometer at room temperature. The nanoparticles exhibited a ferromagnetic behavior with the coercive force (Hc), saturation magnetization (Ms) and remanent magnetization (Mr) was 185.28 Oe and 0.494 emu/g, 0.077 emu/g. 相似文献
16.
Spinel LiMn2O4 crystal with the grain sizes of about 15 nm is firstly synthesized by hydrothermal route at 180 °C using MnO2 as a precursor. The LiMn2O4 powders synthesized by hydrothermal technique and sol-gel reaction were investigated by X-ray diffraction (XRD) and Transmission electron microscopy (TEM). The LiMn2O4 samples were used as cathode materials for lithium-ion battery, whose electrochemical properties were investigated. The results show that the sample obtained by hydrothermal route has higher capacity than that prepared by sol-gel method. 相似文献
17.
Synthesis of nano-particles of anatase-TiO2 and preparation of its optically transparent film in PVA
Anatase-TiO2 nano-particles have been synthesized by using long-carbon chain carboxylic acid and titanium tetrachloride (TiCl4). As-prepared powder has been calcined at 500 °C to obtain highly crystalline TiO2. Broad X-ray diffraction (XRD) pattern of as-prepared as well as calcined powder showed all prominent peaks for tetragonal crystal structure representing anatase-TiO2. The particle diameter by applying Scherrer formula was found to be about 20 nm. It was possible to load as-prepared particles in poly vinyl alcohol (PVA) for optical studies. Optically transparent film showed sharp absorption band for TiO2 nano-particles at ∼ 300 nm. Photoluminescence (PL) studies of the solution showed emission wavelength at about 330 nm. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) revealed that the particles in the film have uniform distribution and even for the powder no agglomeration was observed. Thermal analysis (TGA) showed that the stability of host polymer is enhanced. FTIR spectra showed presence of carboxylate functional group in the powder. 相似文献
18.
Hongxiao Yang 《Materials Letters》2010,64(13):1418-1420
In this work, we demonstrate that monodisperse indium hydroxide (In(OH)3) nanorods constructed with parallel wire-like subunits have been fabricated via a acrylamide-assisted synthesis route without any template. NH3 from the hydrolysis of acrylamide acts as the OH− provider. The structure and morphology of as-prepared products have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and thermogravimetric analysis (TG). A detailed mechanism has been proposed on the basis of time-dependent experimental results. Furthermore, by annealing In(OH)3 precursors at 500 °C for 3 h in air, In2O3 samples were obtained with the designed morphology. 相似文献
19.
Precursors of Co3O4 and Ag/Co3O4 composites with sheet-like shape were synthesized with assistance of ethylene glycol via a solvothermal process. The final samples were obtained by calcining each precursor at 400 °C. The as-prepared samples were identified and characterized by thermogravimetric analysis (TG) and differential thermal gravimetric (DTG) analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE-SEM). The Co3O4 and Ag/Co3O4 composite nanosheets were used as electrocatalysts modified on a glassy carbon electrode for p-nitrophenol and H2O2 reduction respectively in a basic solution. The electrocatalytic results showed that p-nitrophenol could be reduced by pure Co3O4 at a large peak current but a rather higher peak potential, and could be reduced effectively by Ag/Co3O4 composites at lower potential. Ag/Co3O4 composites with 6% Ag displayed the highest electrocatalytic activity for H2O2 reduction at the largest peak current and a lower peak potential. The reduction peak potentials of H2O2 all reduced a great deal using Ag/Co3O4 composite. 相似文献
20.
X.L. DuanD.R. Yuan D. XuM.K. Lu X.Q. WangZ.H. Sun Z.M. WangH.Q. Sun Y.Q. Lu 《Materials Research Bulletin》2003,38(4):705-711
Transparent glass-ceramics containing Co2+:ZnAl2O4 nanocrystals were obtained by the sol-gel process for the first time. The gels of composition 89SiO2-5.9Al2O3-4.9ZnO-0.2CoO (ZAS) were prepared at room temperature, and heat-treated at different temperatures. The microstructure and optical properties of the heated samples were studied by using X-ray diffraction (XRD), transmission electron microscopy (TEM), infrared spectroscopy, and optical absorption spectra. Co2+:ZnAl2O4 nanocrystals were precipitated from ZAS system and dispersed in the SiO2-based glass during heat-treatment in the temperature range 900-1100 °C. Co2+ ions were located in tetrahedral sites in ZnAl2O4 nanocrystals. The Co2+:ZnAl2O4 crystallite size was in the range of 4-15 nm. 相似文献